MME - Research Areas - Trauma Mechanics Projects

The cell stretching project focuses on simulating cell deformation through the use of the Controlled Axonal Injury (CAI) Device. Damaged cell samples are then studied with the use of fluorescence imaging to determine the extent of injury in proportion loading.

Raman Spectroscopy allows us to analyze the neuron, the main structural and functional component of the brain, to help us understand its biochemical, electrical, and mechanical behaviors under different mechanical loadings. If we define the neuron injury level by these behaviors, we can determine its relationship to the loading level. With this information, we can identify upper and lower damage thresholds as a function of strain and strain rate - important parameters for the designing of helmet effective at preventing bTBI.

A supersonic blast wave or shock blast induces an instantaneous increase in atmospheric pressure and causes what is called primary blast injury. Modeling blasts’ effects on rats may help to characterize and understand its mechanisms and so we have begun using three dimensional finite element models of a rat brains and heads to simulate controlled cortical impacts (CCI) and blast loading. Models are developed from MRI images using Avizo© and Mimics13©

Improvised explosive device (IED) is one of the strongest threats in current military operations. IED causes damages in the body of a soldier by applying various external stimuli, e.g., penetration, accelerative loads, overpressure, toxic gases, thermal stimuli, etc. These lead to traumatic damages in various body parts. Among them, traumatic brain injury (TBI) is one of the leading causes of morbidity and death of soldiers. To date, it is not fully understood what physical component of the IED blast causes TBI and how the IED blast induces TBI and its secondary progression at cellular level. In this study, we examine the effects of high pressure impulsive loading, that mimics IED blast conditions, on brain cell response in cell life or death question. We are developing single pulse pressurization equipment (Dr. Feng Group) and assess astrocyte cell response to impulsive pressures in cell proliferation and apoptosis (Dr. Lim Group).

Blast induced traumatic brain injury (bTBI) is signature injury in recent combat scenarios involving improvised explosive devices (IEDs). In 2005, the U.S. military reported 10,953 IED attacks, at an average of 30 per day[2].TBI and concussion rates among service members returning from Operation Iraqi Freedom (OIF) have been reported at 22%. However, the rate of persistent symptoms has been reported as significantly lower (8 %). The goal of this research work is to understand role of protective devices like helmet and body armor under blast loading condition and how they relate to blast mitigation...

Modeling and simulation activities are becoming increasingly important in the area of brain biomechanics with application to primary blast injury (PBI). Although current FE head models include a detailed geometrical description of the head's intracranial contents, there is a crucial lack of material models for the brain which are appropriate to use in blast scenarios analysis, i.e. over a large strain/ very high frequency range.

The external mechanical load will firstly cause the mechanical deformation of neurons, and then, when this deformation reaches to a critical point (threshold), it will initiate the chemical/biological response. The chemical/biological response can cause the neuronal function loss—neuronal injury. This process is considered to be the mechanism of the mild traumatic brain injury (mTBI) at the cellular level. Understanding the relationship between the neuronal mechanical response and their biological responses is the first important step to understand the mechanism of mTBI.

The ‘RED Head’ or ‘Realistic Explosive Dummy Head’ development project focuses on head injuries caused by shock waves generated by explosions. To develop such a head model, materials analysis was performed to find synthetic materials to simulate human head components such as skin, skull and brain. The geometries of these components were carefully controlled to simulate it as a human head surrogate. The head model was instrumented with various sensors to understand the attenuation of the pressure waves through the brain and the flexure of the skull.

Blast-mimicking impulsive pressurization is conducted through use of the Kolsky bar. The direct compression Kolsky bar works by storing strain energy in the bar between the engaged friction clamp and the compressing scissors jack. When the friction clamp is released, by fracturing the locking bolt, the energy in the stored section is released as a near square wave of strain. When the wave reaches an impedance change, such as is at the sample, part of the wave will bounce back while the remainder will pass through the material, in this case an in-vitro cell containment chamber.